Comparison of media in the Anaerobe-Tek and Presumpto plate systems and evaluation of the Anaerobe-Tek system for identification of commonly encountered anaerobes

Abstract

Using a variety of sporeforming and nonsporeforming anaerobic bacteria, we compared 10 differential agar media of the Anaerobe-Tek (A/T) system recently marketed by Flow Laboratories, Inc. (McLean, Va.) with 10 comparable media in Presumpto quadrant plates (Presumpto 1, 2, and 3) developed by the Centers for Disease Control Anaerobic Bacteria Branch. The A/T identification system was evaluated by comparing the species identity of anaerobes determined as recommended by the manufacturer's instruction manual with the identity of the strains obtained by the Centers for Disease Control Anaerobe Reference Laboratory by using conventional procedures. We also compared reactions obtained with the Presumpto plates with a chopped meat glucose broth culture as a source of inoculum with those obtained by using a turbid cell suspension from growth on blood agar as inoculum. The agreement of results for the 16 characteristics compared ranged from 92.8 to 100%. Comparison of test results obtained with 10 media in the Presumpto plate and A/T systems from the examination of 223 strains of anaerobes, representing 54 different taxa, showed the following agreement between A/T and CDC systems: catalase production, esculin hydrolysis, glucose fermentation, and lecithinase production (100%); inhibition of growth by bile agar (99.6%); lipase production (99%); DNase (98.7%); fermentation of lactose and mannitol (98.2%); starch hydrolysis (96.9%); gelatin hydrolysis (96.4%); and casein hydrolysis (94.6%). Of the 204 strains of common anaerobes tested with the A/T system, only 70% were correctly identified to the species level. However, several strains could have been identified correctly with the A/T system if data on certain other characteristics had been included in the A/T data base.